Well I have an empty 55g tank with a Rena filstar xp3 canister filter hooked up to it.
I want a fish only with live rock tank (FOWLR). I want it to be as low maintenance as possible. I would only like to be doing water changes monthly.

My questions are:
what hardy nice looking fish can I get that will do nice in a 55g?
Do you have to have a protien skimmer?
How many fish can i have?
and lastly, what other equiptment do I need?

you will need to do water changes atleast twice a month, if not every week.
skimmers are needed on a tank this size to take the waste and stuff out the water.
And everything else depends on what you like. are there certain fish that catch your eye? most of thae larger one wont be able to go in your tank, but you can go with smaller to medium sized fish.